1. Field of Invention
The present invention relates to a digital demodulator. More particularly, the present invention relates to a digital demodulator and a digital demodulation method.
2. Description of Related Art
The television signal transmission system is widely used today. The conventional receiver of the television signal transmission system comprises a digital demodulator that acts as a frequency phase locked loop (FPLL) to lock the frequency of the input signal. In recent years, digital frequency phase locked loop (DFPLL) is used to replace the FPLL. However, it's hard to detect the proper timing to enlarge or narrow the phase-locked loop bandwidth to lock the frequency of the input signal. If the tuning is not performed on the right time, the performance of the demodulation system will dramatically drop off. Also, a reset step is needed, if the input signal may still fail to be locked in a long time.
Accordingly, how to detect the proper timing for tuning the phase-locked loop bandwidth is the key for a digital demodulator and a digital demodulation method to overcome the above issues. The present invention addresses such a need.